Boost technology in a regulated mod; who can explain how it works?

[stols001]

I'm still here.... Hoping for this.... It's becoming clearer....

Who makes up these magic the gathering quotes, I want to know? "Water shifts and confuses but as ice it holds the stillness of truth." I checked, and "Ariel the whisperer" does not appear to be a real person, although she may be eloquent.

I think I'm getting "You can drop your boost circuit into snow or ice, but don't run it under running water."

I knew I was getting closer....

Anna

 

[zoiDman]

...

A variable wattage ecig varies the voltage across the coil using a circuit similar to the one in Zoidman's video in an earlier post. The faster the VV circuit pulses the voltage, the more often the capacitor charges and discharges. That happens thousands of times per second. When you adjust wattage on your ecig mod, you are adjusting the frequency (number of times per second) that voltage is applied to the coil. The more often it's pulsed the hotter the coil gets (more on time).

This is where I was having the Mental Block.

Because for Some Reason I had it in my Head that the Frequency of Switch Opened/Closed was Fixed. So I had to come up with Ingenious ways for a VV Output Range to be achieved while still maintaining a Flat DC signal.

But once Russom said that the Frequency of the Switch could be changed, I went back and looked at the Video that untar posted and it All Made Sense.

 

[Eskie]

See? This is why the loss of Heathkit in favor of products assembled from inexpensive mass produced ICs has devastated our technological lead over the Soviet Union and left us vulnerable to the communist threat.

Oh wait. I don't think they're around anymore. Now it's just hacking credit cards that excites our kids instead of learning how to use a soldering iron.

 

[DaveP]

This is where I was having the Mental Block.

Because for Some Reason I had it in my Head that the Frequency of Switch Opened/Closed was Fixed. So I had to come up with Ingenious ways for a VV Output Range to be achieved while still maintaining a Flat DC signal.

But once Russom said that the Frequency of the Switch could be changed, I went back and looked at the Video that untar posted and it All Made Sense.

Something like this is what you could expect from bargain ecig mod circuits, especially the cheaper ones that use less expensive circuitry. The more you pay, the more technology you can expect (hopefully). The circuit below shows the output waveform with and without the smoothing capacitor.

This one isn't digital technology. It's just an AC driven circuit using a full wave rectifier circuit that's smoothed and clipped using a filter capacitor. Digital circuits could produce a true square wave right out of the box. The width of the square wave pulse can be controlled through clock speed to raise and lower the effective voltage that the coil sees (the on-off pulse train duty cycle).

 

[zoiDman]

How long does the voltage & current stay at zero?

...

In Calculus terms of, it is Instantaneous.

BTW - I though I read once that for "120 AC", the Peak Voltage is 170. And that the term "120 Volts" is a Geometric Average of the Area under the Curve.

Is that True?

 

[zoiDman]

...

One Step at a Time Dave.

I'm still Basking in the Glow of finally Understanding a 1st Semester Electronics problem.

 

[DaveP]

See? This is why the loss of Heathkit in favor of products assembled from inexpensive mass produced ICs has devastated our technological lead over the Soviet Union and left us vulnerable to the communist threat.

Oh wait. I don't think they're around anymore. Now it's just hacking credit cards that excites our kids instead of learning how to use a soldering iron.

Heath and Knight kits are what helped me solidify my life career ambitions. I was hooked the first time I turned on a kit built from boxed parts. That led to electronics school, computer science, and a life long career.

 

[ScottP]

Heath and Knight kits are what helped me solidify my life career ambitions. I was hooked the first time I turned on a kit built from boxed parts. That led to electronics school, computer science, and a life long career.

I actually still have a Heathkit. Haven't touched it since the early 90's.

 

[Rossum]

In Calculus terms of, it is Instantaneous.

Exactly! In other words, the time for which it's actually OFF is effectively nil.

BTW - I though I read once that for "120 AC", the Peak Voltage is 170. And that the term "120 Volts" is a Geometric Average of the Area under the Curve.

Is that True?

Yes. The peak voltage is around 170. The nominal 120V is the RMS value, which coincides with the DC voltage that you would need to use to get the equivalent results in a resistive load like an incandescent bulb.

 

[zoiDman]

Exactly! In other words, the time for which it's actually OFF is effectively nil.


Yes. The peak voltage is around 170. The nominal 120V is the RMS value, which coincides with the DC voltage that you would need to use to get the equivalent results in a resistive load like an incandescent bulb.

Thanks Rossum.

Hey BTW, I got thinking More about that Boost Circuit switching On/Off. And realized that not Only does it have to alter the Duty Cycle depending on what Output the user wants. But also due to the Charge State the battery currently has.

ie: When it is freshly charged at 4.2 Volts verses when it has be discharged down to say 3.4 Volts. And everything in between.

 

[Rossum]

When it is freshly charged at 4.2 Volts verses when it has be discharged down to say 3.4 Volts. And everything in between.

Or as the voltage sags under load. We tend to ignore the fact that the battery voltages we talk about are no-load voltages that a battery cannot deliver it an actual load. Look at some of Mooch's older pulse tests and you'll see this is quite a substantial factor. Moreover, the amount of sag in a 5 second pulse is not steady either.

 

[zoiDman]

Or as the voltage sags under load. We tend to ignore the fact that the battery voltages we talk about are no-load voltages that a battery cannot deliver it an actual load. Look at some of Mooch's older pulse tests and you'll see this is quite a substantial factor. Moreover, the amount of sag in a 5 second pulse is not steady either.

A Very Good Point.

It is Easy sometimes to View things from a Static Perspective. And not to see them as a Dynamic Process.

 

[DaveP]

Zoidman, being a higher math type you might like this tutorial of how a waveform is approximated to an equivalent DC value. There's lots of interesting electronics math on the site.

https://www.electronics-tutorials.ws/accircuits/rms-voltage.html

 

[zoiDman]

Zoidman, being a higher math type you might like this tutorial of how a waveform is approximated to an equivalent DC value. There's lots of interesting electronics math on the site.

https://www.electronics-tutorials.ws/accircuits/rms-voltage.html

Yeah... That is why I asked Rossum about the Peak Voltage.

From your Link...

A periodic sinusoidal voltage is constant and can be defined as V(t) = Vmax*cos(ωt) with a period of T. Then we can calculate the root-mean-square (rms) value of a sinusoidal voltage (V(t)) as:

Integrating through with limits taken from 0 to 360 or “T”, the period gives:

Where: Vm is the peak or maximum value of the waveform. Dividing through further as ω = 2π/T, the complex equation above eventually reduces down too:

RMS Voltage Equation

 

[zoiDman]

BTW...

.7071 is the cos(45 degrees)

It is Also the sin(45 degrees)

Since 1, 1, 2^1/2 are the Sides of a 45, 45, 90 Triangle.

 

[DaveP]

In my 1970s electronic school they just told us to use .707 for the constant and gave us a baseline explanation illustrated with graphics as to how and why it works. Rocket scientists take it much further.

 

[zoiDman]

In my 1970s electronic school they just told us to use .707 for the constant and gave us a baseline explanation illustrated with graphics as to how and why it works. Rocket scientists take it much further.

Yeah... "Seventy Seventy One" (or ∏/4 when in Radians) comes up a Lot when doing 2D Spatial Math.

BTW - This is a Good RMS overview which shows the Half-Angle/Double Angle Identity needed and the implied u/du Substitution needed to do that AC RMS Integration.

https://www.raeng.org.uk/publications/other/8-rms

Also has a few Interesting Examples of how RMS Value can have some other usages.

 

[Rossum]

https://www.raeng.org.uk/publications/other/8-rms

Also has a few Interesting Examples of how RMS Value can have some other usages.

What do AC meters show? Is it the RMS or peak voltage? AC voltmeters and ammeters show the RMS value of the voltage or current.

Provided the voltage being measured is a nice, clean sine wave, that's usually true. But cheap meters generally do a poor job if the voltage is anything else, e.g. the signal coming out of a typical lamp dimmer:

If the meter isn't spec'd as being a "True RMS" meter, you won't get useful readings if you try to measure a signal like that.

 

[DaveP]

If we're designing Voyager 3 the math has to be precise. For most other practical purposes, .707 works every time to approximate the DC equivalent of a sinusoidal waveform..

 

[Rossum]

For most other practical purposes, .707 works every time to approximate the DC equivalent of a sinusoidal waveform..

Sure, for a clean sinusoidal waveform. But use a 'scope to have a look at the "modified sine wave" that you get on the output of a reasonably priced UPS when it's running on batteries, or the chopped sine wave from a lamp dimmer, or the output of a ferroresonant "constant voltage" transformer. In all of these cases (and many others) you cannot just measure the peak voltage and multiply by 0.707 because doing so will get you terribly inaccurate results.